PSYNC

An internal command used in replication.

Browse all commands · Upstream source documentation

Reference field	Value
Canonical name	PSYNC
Catalog group	Server commands
Upstream since	2.8.0 — upstream Redis/module version, not an ffkv release
Pinned catalog	Redis 8.10.0

Syntax

PSYNC replicationid offset

ffkv behavior and limits

Server introspection describes ffkv, not a Redis process. MEMORY reports owned-allocation estimates, not jemalloc accounting. Administrative changes can affect all clients or persistent data; consult the scenario and operations guide before using destructive forms.

Source: README.md:393–395, 601–642; tests/bdd/features/server.feature; tests/bdd/features/catalog.feature.

Native RESP replication is asynchronous and distinct from HTTP snapshot polling. WAIT/WAITAOF barriers belong on the writing connection; acknowledgements do not certify failover safety. Upstream network policy and persistent storage must be configured deliberately (README.md:601–628).

All requests share the 8 MiB framing/1,024-argument ingress limit; normal RESP replies have 64 MiB wire/logical budgets with bounded nesting/value counts. Management and Lua origins impose smaller budgets. These are not a process RSS cap. Catalog inclusion is not exhaustive option or wire-format parity. See limits and compatibility.

Upstream metadata

The following fields come from the pinned Redis metadata, not measured ffkv performance or an assertion that ffkv enforces every upstream flag. Running COMMAND INFO/COMMAND DOCS describe the current engine.

Upstream arity: -3 (includes the command name; a negative number is a minimum).

Command flags: NO_ASYNC_LOADING, ADMIN, NO_MULTI, NOSCRIPT.

Argument structure

Argument	Type	Constraints / metadata
replicationid	string	Required
offset	integer	Required

Additional pinned upstream metadata

{
  "group": "server",
  "since": "2.8.0"
}

Metadata source · Local snapshot: src/command_metadata.json, key psync.

BDD coverage and source examples

These are source observations, not a test run performed by this documentation build. A tag identifies scenario intent; an extracted vector identifies a command invocation, which may intentionally produce an error. Scenarios may require setup, multiple connections, persistence, cluster nodes or native-module fixtures.

• Reconnection requests exactly the missing bytes without another snapshot — tests/bdd/features/replication.feature:109; command tag.
• Wrong history and evicted history transfer a valid bounded RDB — tests/bdd/features/replication.feature:137; command tag.
• Protected-network refusal does not leak upstream credentials or install data — tests/bdd/features/replication.feature:367; command tag.

Scenario tags are present, but no safely parsed JSON command vector was extracted. Consult the named feature source for fixture-driven or parameterized execution; no executable example is invented here.